Display screen or portion thereof having a graphical user interface for button menus



FIG. 1 is a front view of a display screen or portion thereof having a graphical user interface for button menus showing my new design; and,

FIG. 2 is a front view of a second embodiment of a display screen or portion thereof having a graphical user interface for button menus showing my new design.

The outermost broken lines and the broken line showing of rounded shapes illustrate an electronic device and the remaining broken lines illustrate portions of the graphical user interface. None of the broken lines form part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof having a graphical user interface for button menus, as shown and described. 